Topical Enzyme-Replacement Therapy Restores Transglutaminase 1 Activity and Corrects Architecture of Transglutaminase-1-Deficient Skin Grafts

Abstract

Transglutaminase-1 (TG1)-deficient autosomal-recessive congenital ichthyosis (ARCI) is a rare and severe genetic skin disease caused by mutations in TGM1. It is characterized by collodion babies at birth, dramatically increased transepidermal water loss (TEWL), and lifelong pronounced scaling. The disease has a tremendous burden, including the problem of stigmatization. Currently, no therapy targeting the molecular cause is available, and the therapeutic situation is deplorable. In this study, we developed the basis for a causative therapy aiming at the delivery of the enzyme to the inner site of the keratinocytes' plasma membrane. We prepared sterically stabilized liposomes with encapsulated recombinant human TG1 (rhTG1) and equipped with a highly cationic lipopeptide vector to mediate cellular uptake. The liposomes overcame the problems of insufficient cutaneous delivery and membrane penetration and provided excellent availability and activity of rhTG1 in primary keratinocytes. To demonstrate the general feasibility of this therapeutic approach in a humanized context, we used a skin-humanized mouse model. Treatment with rhTG1 liposomes resulted in considerable improvement of the ichthyosis phenotype and in normalization of the regenerated ARCI skin: in situ monitoring showed a restoration of TG1 activity, and cholesterol clefts vanished ultrastructurally. Measurement of TEWL revealed a restoration of epidermal barrier function. We regard this aspect as a major advance over available nonspecific approaches making use of, for example, retinoid creams. We conclude that this topical approach is a promising strategy for restoring epidermal integrity and barrier function and provides a causal cure for individuals with TG1 deficiency.

Recent advances in topical delivery of proteins and peptides mediated by soft matter nanocarriers

“…Indeed, at least two clinical trials aiming for transcutaneous vaccine delivery via the hair follicles were initiated or conducted just recently. Moreover, recent studies provided the proof of concept for a local protein substitution therapy which may open a new treatment option for severe skin diseases (Aufenvenne et al, 2013;Stout et al, 2014). These studies, however, are at a very early stage so that further investigations are crucial to allow for conclusions about the practicability of this approach.…”

“…Aufenvenne et al (2013) developed sterically stabilized liposomes, equipped with a cationic lipopeptide, and encapsulated recombinant human transglutaminase 1 (molecular mass 92 kDa) in order to address the underlying cause of autosomal recessive congenital ichthyosis. The unilamellar vesicles were composed of phosphatidylcholine and poly(ethylene glycol)-2000-dipalmitoyl-phosphatidylethanolamine and were about 200 nm in size.…”

Update on autosomal recessive congenital ichthyosis: mRNA analysis using hair samples is a powerful tool for genetic diagnosis

“…Recently, Aufenvenne et al [34] have developed the basis for an enzyme-replacement therapy for individuals suffering from TGase1-deficient ARCI. They demonstrated that a topical approach using a formulation of liposomal-encapsulated recombinant human TGase-1 is suitable for restoring TGase-1 activity in the upper stratified layers of the epidermis to reconstitute epidermal integrity and barrier function in a mouse model.…”

Transglutaminases in autoimmune and inherited skin diseases: The phenomena of epitope spreading and functional compensation

“…All these steps have been realized . A skin humanized mouse model was developed in which human skin equivalents of TG1‐deficient patients were grafted onto athymic nude mice.…”